The present invention relates to a tool, in particular for an electric screwdriver with a self-locking tool holder, which can be unlocked through pushing a sleeve opposite to the direction of insertion.
U.S. Pat. No. 6,695,321 discloses a tool holder for a screwdriver bit. The locking of the tool occurs manually. A ball partially protruding into the receiving area is held in a starting position through an actuating sleeve in a radial direction. The user can push the actuating sleeve along an axis and lift the hold. Upon insertion of the screwdriver bit, the ball moves aside in a radial direction. A spring pushes the actuating sleeve into the starting position.
U.S. Pat. No. 7,469,909 discloses a tool holder which automatically locks a screwdriver bit. The user inserts a screwdriver bit in the direction of insertion into a receiving area of the tool holder. A locking ball lies in a slot and partially protrudes into the receiving area. The screwdriver bit pushes the ball into the slot. The locking ball is initially held in a radial direction through an interior face of an actuating sleeve. The interior face expands conically in the direction of insertion, such that the locking ball can exit the receiving area radially near the machine-side end of the slot. The ball falls back into the receiving area when the locking groove of the screwdriver bit reaches the end of the slot. A spring pushes the locking ball to the tool-side end of the slot and the tapered end of the interior face of the actuating sleeve. To unlock, the user pushes the actuating sleeve opposite to the direction of insertion and pulls out the screwdriver bit. The locking ball moves aside in a radial direction.
The tool holder according to the invention has a tubular main part, a locking element, and an actuating sleeve. The tubular main part features a prismatic receiving area coaxial to a working axis for receiving a tool and a first radial channel. The locking element can be moved along the first radial channel in a radial direction between a position partially protruding into the receiving area and a position retracted from the receiving area. The actuating sleeve can be moved on the main part along the working axis between a locking position for locking the tool in the receiving area and a removal position for removing the tool from the receiving area. The actuating sleeve has a stop face and a pocket. In the locking position, the stop face overlaps with the first radial channel, and the locking element is obstructed by the stop face in the position protruding into the receiving area. In the removal position, the pocket overlaps with the first radial channel and the locking element is moveable in the position retracted from the receiving area by the locking element partially submerging in the pocket. A spring pre-tensions the actuating sleeve in the direction from the removal position into the locking position.
The main part has a depression on the outside and a second radial channel which passes into the receiving area starting from the depression. The actuating sleeve has a radially pre-tensioned latching element, which engages into the depression in the removal position. An ejection element is guided in the second radial channel, the ejection element being pushed into a position which partially protrudes into the receiving area and pushes the latching element out of the depression in a position which is retracted from the receiving area. The actuating sleeve remains in the removal position. The insertion of a tool is hereby facilitated. By pushing the ejection element out of the receiving area, the tool unlocks the actuating sleeve, which then, driven by the spring, automatically locks.
The tool holder requires no locking elements moved parallel to the working axis in order to be able to insert a tool without activation of the actuating sleeve. The tool holder is correspondingly shorter. Additionally, no spring is needed to hold the locking element in a slot in its position. These springs impede the mounting of tool holders.